Water Recycling System for Mobile Surface Cleaners

ABSTRACT

A mobile surface cleaner has a mobile body configured to travel to areas to be cleaned. A dispensing system attached to the mobile body dispenses liquid on a surface as dispensed liquid. A recovery system attached to the mobile body recovers dispensed liquid as recovered liquid. A regenerative media filter attached to the mobile body filters the recovered liquid to form filtered liquid that can be dispensed by the dispensing system.

CROSS-REFERENCE TO RELATED APPLICATION

The present application is based on and claims the benefit of U.S. provisional patent application Ser. No. 61/926,788, filed Jan. 13, 2014, the content of which is hereby incorporated by reference in its entirety.

FIELD OF THE DISCLOSURE

The present disclosure relates to mobile cleaning and/or sanitizing systems, and more particularly but not limited to systems that recover liquids.

BACKGROUND

A wide variety of systems are in use today for cleaning or disinfecting surfaces in residential, industrial, commercial, hospital, food processing, and restaurant facilities, such as floors covered with tile or other substrates.

For example, hard floor surface scrubbing machines are widely used to clean the floors of industrial and commercial buildings. They range in size from a small model, which is controlled by an operator walking behind it, to a large model, which is controlled by an operator riding on the machine. Such machines in general are wheeled vehicles with suitable operator controls. Their bodies may contain power and drive elements, a source tank to hold a cleaning liquid, and a recovery tank to hold soiled liquid recovered from the floor being scrubbed. A scrub head, which contains one or more scrubbing brushes and associated drive elements, is attached to the vehicle and may be located in front of, under or behind it. A solution distribution system dispenses cleaning liquid from the source tank to the floor in the vicinity of the scrubbing brush or brushes.

Soft floor cleaning machines can be implemented as small mobile machines that are handled by an operator or can be implemented in a truck-mounted system having a cleaning wand connected by a hose to the truck. The truck carries a cleaning liquid source tank, a waste liquid recovery tank and a powerful vacuum extractor.

SUMMARY

A mobile surface cleaner has a mobile body configured to travel to areas to be cleaned. A dispensing system attached to the mobile body dispenses liquid on a surface as dispensed liquid. A recovery system attached to the mobile body recovers dispensed liquid as recovered liquid. A regenerative media filter attached to the mobile body filters the recovered liquid to form filtered liquid that can be dispensed by the dispensing system.

In a further embodiment, an apparatus has a movable body and a tank movable with the movable body. The tank receives liquid recovered from an external surface and a regenerative media filter movable with the movable body filters liquid from the tank to form filtered water that can be dispensed on an external surface for cleaning.

In a further embodiment, a machine-implemented method involves dispensing liquid from a mobile cleaner on a surface to be cleaned, drawing the dispensed liquid into the mobile cleaner to form recovered liquid, passing the recovered liquid through a regenerative media filter in the mobile cleaner to form filtered liquid, and dispensing the filtered liquid from the mobile cleaner on a surface to be cleaned.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a cleaning machine in one embodiment.

FIG. 2 is a cross-sectional side view of a regenerative media reservoir.

FIG. 3 is a cross-sectional side view of a regenerative media filter under one embodiment.

FIG. 4 is a cross-sectional side view of a regenerative media filter under a second embodiment.

FIG. 5 is a block diagram of electrically controlled elements in the cleaning machine of FIG. 1.

FIG. 6 is a flow diagram of a method of operating a cleaning machine with regenerative media filters.

FIG. 7 is a schematic diagram of the cleaning machine of FIG. 1 in a filtering mode.

FIG. 8 is a cross-sectional side view of a regenerative media filter of a first embodiment with an applied regenerative media layer.

FIG. 9 is a cross-sectional side view of the filter of FIG. 4 with an applied regenerative media layer.

FIG. 10 is a schematic diagram of the cleaning machine of FIG. 1 in a regeneration mode.

FIG. 11 is a schematic diagram of the cleaning machine of FIG. 1 in a state requiring replacement of regenerative media.

FIG. 12 is a partial cross-sectional side view of one embodiment of a mobile cleaning machine.

FIG. 13 provides an alternative construction of regenerative media filters 148 and 150 and regenerative media reservoir 146.

FIG. 14 provides a perspective view of a further embodiment of a regenerative media filter.

FIG. 15 provides a front view of the regenerative media filter of FIG. 14.

FIG. 16 provides a back view of the regenerative media filter of FIG. 14.

FIG. 17 provides a left side view of the regenerative media filter of FIG. 14.

FIG. 18 provides a right side view of the regenerative media filter of FIG. 14.

FIG. 19 provides a sectional view of the regenerative media filter of FIG. 14.

FIG. 20 provides an exploded side view of the regenerative media filter of FIG. 14.

FIG. 21 provides a sectional view showing a plug of regenerative media paste being added to a regenerative media reservoir.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

The efficiency of operating mobile cleaning machines of the past is dictated in part by how often the operator has to refill the source liquid tank and empty the recovery liquid tank. The refilling and dumping operation takes a significant amount of time and therefor has a direct effect on how long it takes the operator to clean an area.

Embodiments described below improve the efficiency of operating a cleaning machine by filtering recovered liquid to form filtered liquid that is then used as a cleaning liquid by the cleaning machine. This filtering reduces the amount of liquid in the recovery tank while also providing a new source of cleaning liquid for the mobile cleaning machine. Thus, by filtering the recovered liquid, embodiments described below extend the period of time during which the cleaning machine can be used without an interruption for refilling the source tank or emptying the recovery tank.

The embodiments described below use a regenerative media filter that utilizes a screen coated with a layer of regenerative material. During filtering, the exterior of the layer of regenerative material becomes embedded with contaminants causing a drop in the flow rate through the filter and an increase in pressure upstream of the filter. The filter may then be regenerated by disturbing the layer of regenerative material so that it is redistributed on the screen. During the redistribution, elements of the regenerative media that are not embedded with contaminants may be deposited on the exterior of the new layer of regenerative material and thus are available to filter contaminants from the liquid. Such redistributions of the regenerative material may be performed passing filtered liquid backwards through the filter, by mechanically agitating the media itself, or by a combination of the two. The media which has been dislodged will become re-suspended in the fluid and will re-deposit on the screens when filtration flow resumes. The regenerative material layer may be regenerated multiple times before the regenerative media is replaced.

FIG. 1 provides a schematic diagram of a mobile surface cleaner 100 under one embodiment. Mobile surface cleaner 100 includes a mobile body 102 that moves along a surface 104 on one or more wheels 106, 108 such as direction 109 to travel to areas to be cleaned. Mobile surface cleaner 100 includes a dispensing system 103 that dispenses a cleaning liquid 112 onto surface 104 and a recovery system 105 that recovers at least a portion of the dispensed liquid from surface 104. Regenerative media filters 148 and 150 are attached to mobile body 102 for filtering the recovered liquid to form filtered liquid that can be dispensed by dispensing system 103.

In this example, dispensing system 103 includes a source tank 130 that holds a source liquid to be applied to surface 104 and dispenser 110 that dispenses or sprays the cleaning liquid on surface 104 or onto a cleaning tool connected to mobile body 102. Dispenser 110 may be fixed to mobile body 102 or may be part of a spray wand or other accessory tool that is attached to mobile body 102, such as by a hose, or the dispenser may be as simple as the end of a hose out of which the cleaning liquid flows. In addition, although surface 104 is shown below mobile body 102, surface 104 may be any surface that dispenser 110 can apply liquid to and from which recovery system 105 can recover liquid. Dispensing system 103 optionally includes a dispensing pump 132 to pressurize the cleaning liquid and also optionally includes an electrolysis unit 134 that applies an electrical field to the source liquid to improve the cleaning properties of cleaning liquid 112. In some embodiments, however, no electrolysis unit or pump are used, and the cleaning liquid flows by gravity out of the source tank and the flow is regulated by means of a manual or electrically controlled valve instead of dispensing pump 132.

The cleaning liquid 112 interacts with dirt and other contaminants on surface 104 to produce a dirty or soiled liquid 114 that is recovered from surface 104 by recovery system 105. Recovery system 105 includes a recovery device 116, a recovery tank 118, and a vacuum source 120. Recovery device 116 takes the form of a vacuumized squeegee in some embodiments. The squeegee is connected by a flow path 117 to recovery tank 118. Vacuum source 120, which can include a fan or a pump, creates a low pressure (below ambient atmospheric pressure) in recovery tank 118 that draws water from surface 104 along path 117 into recovery tank 118.

The dirty liquid 114 passes through an initial filter 122 to produce initial recovered liquid 124. In some embodiments, initial filter 122 is a coarse screen fabricated from either disposable plastic mesh or a stainless steel mesh. In some embodiments, initial filter 122 has openings with widths of 1.5 mm-5 mm, and in one embodiment has openings with widths of 3 mm. Initial filter 122 is designed to trap debris larger than the openings in the mesh such as nuts, bolts, wood chips, metal shavings and so forth.

Initial recovered liquid 124 is then further filtered by a secondary filter 126. In some embodiments, this filter or filters are arranged so that they extend across the entire width of recovery tank 118 to divide recovery tank 118 into separate halves and as the liquid 124 flows through filter 126, the liquid becomes secondary recovered liquid 128, which is generally cleaner than initial recovered liquid 124. Secondary filter 126 is a finer filter than initial filter 122 and in some embodiments is constructed of a mesh with an aperture size of 0.10 mm-1.0 mm and in one embodiment has openings of size 0.25 mm. The mesh may be made of any suitable material such as plastic or stainless steel. Secondary filter 126 may be backwashed to remove filtered material from the mesh screen without removing secondary filter 126 from recovery tank 118 or it may be constructed to allow easy removal for cleaning.

In one example, mobile surface cleaner 100 has a non-recycling mode and a recycling mode and a user is able to switch between the two modes using a mode switch 136. In the non-recycling mode, liquid vacuumed into recovery tank 118 remains in tank 118. In the recycling mode, secondary recovered liquid 128 is additionally filtered using a suction filter 140 and regenerative media filters 148 and 150 to produce filtered liquid that is returned to source tank 130. In one example, suction filter 140 is a mesh screen made of a suitable material such as plastic or stainless steel with an aperture size of 0.10-1.0 mm, and in one embodiment of size 0.25 mm, that acts as a pump inlet screen. Regenerative media filters 148 and 150 use a combination of a screen with a layer of regenerative material over the screen to further filter the liquid. In the example of FIG. 1, a filter pump 138 draws secondary recovered liquid 128 through filter 140 and pumps it through a valve assembly 142, a conduit 184 attached to a regenerative media reservoir or regenerative media charging vessel 146 and then through regenerative media filters 148 and 150 to produce a filtered liquid 152 that flows through conduit 159, a source tank valve 161 and conduit 164 and into source tank 130. Although FIG. 1 shows two regenerative media filters 148 and 150, it is envisioned that one such filter, or three or more such filters, could be employed. Also note that if valve 161 is closed and valve 162 is open, the filtered liquid will be directed back to the recovery tank 118 through conduit 165. This possibility allows the flow rate and operation of the filtration system to be independent of the cleaning process, i.e. filtration can be done at a higher rate and during longer times than only the time when solution is being dispensed from the solution tank.

FIG. 2 provides a cross-sectional side view of an exemplary regenerative media charging vessel or reservoir 146, which is initially loaded with clean regenerative media 200. Regenerative media 200 can include diatomaceous earth, perlite, silica dioxide, activated carbon, cellulose fiber and rice hull ash, for example. Regenerative media 200 is loaded into regenerative media reservoir 146 by placing it in a removable container 202, which is then screwed into a cap 204. Removable container 202 may be a disposable container such that its operational lifetime is expected to be less than the lifetime of cap 204. For example, the disposable container may have an expected operational lifetime that is less than half of the expected operational lifetime of cap 204. In another example, removable container 202 may be used repeatedly by cleaning removable container 202 and filling removable container 202 with new regenerative media. In another embodiment, the regenerative media 200 may be mixed with water or another liquid or binding agent to produce a paste or a solid dissolvable cake that can be measured and handled more easily. By mixing regenerative media 200 with a liquid, the production of harmful dusts when replacing regenerative media 200 can be reduced. Other materials can also be blended in wet or dry form with the filter media to enhance filtration, add or counteract various odors, or perform other functions. For example, water soluble salts or bleach may be added.

At the beginning of operation, the regenerative media filter system is normally operated for at least a few minutes with clean water to initially coat the regenerative media filters with regenerative media. In this mode, clean water is placed in the recovery tank and pumped into the regenerative media reservoir 146. In this mode or later when mobile surface cleaner 100 is filtering recovered liquid, the liquid enters an inlet 206 in cap 204, passes through an opening 208 in cap 204 and down a tube 210 into an interior 212 of removable container 202, as shown by the dotted line arrows in FIG. 2. Within container 202, the liquid interacts with the regenerative media 200 to form a slurry that eventually fills interior 212 and then exits through an opening 214 in cap 204. The slurry then exits cap 204 through an outlet 216 toward regenerative media filters 148 and 150. In the filters 148 and 150, the slurry will coat the filters as described in subsequent paragraphs and perform fine filtration. It is not necessary for all of the media to be transferred from media reservoir 146 into filters 148 and 150 for filtration to begin, but at least a partial coating of media on the filter elements is needed to start effective filtration. In accordance with some embodiments, a full coating on the filters is achieved after five minutes of pumping and a coating sufficient for effective filtering is achieved after two to three minutes of pumping.

FIGS. 3 and 4 provide side cross-sectional views of two different exemplary embodiments of the regenerative media filters 148 and 150. In FIG. 3, a regenerative media filter 300 is provided and in FIG. 4, a regenerative media filter 400 is provided.

Regenerative media filter 300 includes a cap 302 and a removable container 304 that screws into cap 302. A septum or filter media support structure 306 extends from cap 302 into a space 314 of removable container 304 such that space 314 extends around all sides of septum 306. Septum 306 includes an internal support structure 318, which may be formed of a grid or a perforated tube of rigid material such as plastic to define a hollow chamber 319. A screen or media support 320 is applied to support structure 318. Both support structure 318 and screen 320 are perforated so that liquid may pass through both. In accordance with one embodiment, screen 320 has aperture sizes on the order of 100 microns. In accordance with one embodiment, screen 320 is made of woven stainless steel but may also be made of woven nylon or some other suitable material.

Filter 300 is attached to conduits carrying liquids using ports 308 and 310 in cap 302. Openings 312 and 316 in cap 302 allow liquid from the conduits to enter and exit space 314 and hollow chamber 319, respectively.

In other embodiments, an outer layer of fine screen material 320 is bonded to support structure 318 and may be constructed of stainless steel, nylon or other resilient filtering materials. The openings in this fine screen material may be in the range of 25 to 250 microns, and in the preferred embodiment the openings in the screen are approximately 100 microns. In other embodiments, the septum may be constructed of a stack of wafers that are stacked around support structure 318 such that support structure 318 extends through the center of each wafer. In any case, the size of the openings in the septum must be such that the filter media is effectively prevented from passing through the septum and the media is retained on the surface of the septum.

Filter 400 of FIG. 4 includes a cap 402, a removable container 404 and septa or filter structures 406, 408, 410 and 412. Although only four filter structures are shown in FIG. 4, those skilled in the art will recognize that more septa may be present and in accordance with one embodiment, sixteen septa are present. Cap 402 includes two ports 419 and 422 that are connected to conduits to allow liquid in the conduits to flow through the filter. Filter 400 also includes a central inlet tube 414 that is in communication with an opening 421 in cap 402 to allow liquid to flow between port 419 and interior space 405 of removable container 404.

Septa 406, 408, 410 and 412 have similar structures to each other and may be constructed in any of the configurations described in preceding paragraphs, according to FIG. 3. The structure of septum 406 is described below and this description applies to septa 408, 410 and 412 as well. Septum 406 includes a support structure 415 that defines a hollow chamber 416 and provides a structural support for one or more screen layers such as screen layer 418, which is secured around support structure 415. Screen layer 418 is constructed of woven stainless steel in one embodiment but may be constructed of woven nylon or any other resilient screening material with sufficiently small openings to prevent the regenerative material from passing while allowing liquid to pass. Septa 406, 408, 410 and 412 are each supported by a plate 420 that includes an opening for each septum and an opening for inlet tube 414. The tops of each septum 406, 408, 410 and 412 are in fluid communication with an opening 426 in cap 402 to allow fluid to flow between hollow chambers 416 and port 422.

FIG. 5 provides a block diagram showing example connections between electrical elements in mobile surface cleaner 100. The operation of mobile surface cleaner 100 is controlled in part by a controller 198 through electrical connections to vacuum source 120, dispensing valve and/or dispensing pump 132, filter pump 138, optional electrolysis cell 134, valve assembly 142, bypass valve 162, source tank valve 161, air vent valve 163 and mode switch 136. In addition, controller 198 receives sensor inputs from a pressure sensor 190 located on a conduit 184 between filter pump 138 and regenerative media filters 148 and 150. Controller 198 also receives sensor signals from a low-level detector sensor 192 and a high-level detector sensor 194 that are both mounted within recovery tank 118. Note that although two separate level detectors are depicted in the figures, a single level detector that is capable of detecting both a high level and a low level in the tank may be used in place of two separate level detectors. Typically the high level detector is used only to detect a “tank full” condition (and shut off the vacuum motor) whereas the low level detector is used to control the filtration and recycling system. Other means of detecting the level of fluid in the recovery and solution tank and using this information to control the operation of the pump and valves should be obvious to one skilled in the art. Controller 198 also controls an optional sensory indicator 196 that indicates that a “tank full” condition, which is also an indication that the regenerative media should be replaced as described in more detail below. Controller 198 is connected to a power source 550 through a switch 552. Controller 198 includes a memory 502 and a processor 504 that together are capable of implementing a timer 500 and of executing instructions stored in memory 502 for controlling mobile surface cleaner 100 as described further below.

FIG. 6 provides a flow diagram of an exemplary method implemented through the execution of instructions stored in memory 502 by processor 504 for controlling mobile surface cleaner 100 when mobile surface cleaner 100 is in a recycling mode. At step 600, the regenerative media filters are primed. When mobile surface cleaner 100 is initially started, priming the regenerative media filters in one example involves placing new regenerative material in media reservoir 146, filling recovery tank 118 to ninety percent capacity with clean liquid, filling source tank 130 to fifty percent capacity with clean liquid and running filter pump 138 for several minutes.

When controller 198 activates filter pump 138, liquid from recovery tank 118 is drawn through pump inlet screen 140 and pumped into conduit 184 attached to regenerative media reservoir 146. The fluid passing through conduit 184 initially mixes with the new regenerative media in removable container 202 to form a slurry, which moves out of removable container 202 and into the containers of regenerative media filters 148 and 150. The regenerative media forms a layer or cake against the screens of the septa of regenerative media filters 148 and 150. This cake is porous but has a mean pore size much finer than the screens on the septa, thus providing a finer degree of filtration than would be possible with a metal or plastic screen itself. Liquid from recovery tank 118 is filtered by the layer of regenerative media to form filtered liquid 152, which then enters source tank 130 through source tank valve 161. The flow of liquid during step 600 is shown in the schematic diagram of FIG. 7 where the solid arrows indicate the direction of fluid flow. In FIG. 7, bypass valve 162 is closed and source tank valve 161 is open so that liquid flows into source tank 130 and not back into recovery tank 118. One embodiment of the invention prescribes that the process start with recovery tank 118 nearly full and source tank 130 half full of clean solution. Other filling percentages can be used in other embodiments, as long as there is sufficient liquid in recovery tank 118 to effect the priming of the filters and maintain flow until additional liquid is recovered from the floor 104. In this example, the regenerative media filters are primed after recovered liquid passes through recovery tank 118 and into media reservoir 146 and filters 148, 150. An alternate embodiment would allow only a portion of the regenerative media to be used at startup and would meter the remaining media into the liquid stream over the course of ongoing filtration.

FIG. 8 provides a cross-sectional side view of filter 300 of FIG. 3 showing a layer of regenerative media 800 formed on outer screen 320. As depicted by the dotted arrows in FIG. 8, during step 600, liquid from recovery tank 118 enters filter 300 through port 308. The liquid carries regenerative material from regenerative media reservoir 146 to form regenerative media layer 800 on support screen 320. After depositing the regenerative media, the liquid passes through support screen and support structure 318 to reach hollow chamber 319. The liquid then moves upward through hollow chamber 319 and cap opening 316 and eventually out port 310.

FIG. 9 shows a cross-sectional side view of filter 400 of FIG. 4 showing a layer of regenerative media formed on screen 418 of each septum 406, 408, 410 and 412. In particular, layers 900, 902, 904 and 906 have been formed on respective septa 406, 408, 410 and 412. As depicted by dotted arrows in FIG. 9, during step 600, liquid carrying regenerative media enters filter 400 through port 419 and travels down center tube 414 to enter interior space 405 of container 404. The liquid then passes through the various septa while depositing regenerative media on the exterior of the septa to form regenerative media layers 900, 902, 904 and 906. The liquid then passes through hollow chambers 416 of support structures 415 and hole 426 in cap 402 before finally exiting through port 422.

Returning to FIG. 6, note that when the machine is turned on and mode switch 136 is in the recycle position, the filter pump 138 is immediately turned on. At step 601, controller 198 compares the level of liquid in recovery tank 118 to a first threshold. This comparison is done by determining whether the low level detector 192 indicates that the liquid is above or below the low level threshold. If the liquid in recovery tank 118 is below the threshold at step 602, controller 198 changes the states of bypass valve 162 and source tank valve 161 to return liquid to recovery tank 118 instead of providing the liquid to source tank 130. Specifically, controller 198 opens bypass valve 162, closes valve 161 and returns to step 600. Controller 198 then loops between steps 601 and 602 until the level of liquid in the recovery tank exceeds the low level threshold.

As mobile cleaner 100 is used to clean surface, recovered liquid is pulled into recovery tank 118 and is filtered by filters 122 and 126 to form secondary filtered liquid 128. This causes the level of the liquid in recovery tank 118 to rise. When the liquid in recovery tank 118 rises above the low level threshold, controller 198 opens valve 161 and closes valve 162, causing secondary filtered liquid 128 to be pumped through pump inlet filter 140, conduit 184, media reservoir 146, and regenerative media filters 148 and 150. As fully filtered liquid 152 it then passes though conduit 159, valve 161 and conduit 164 and into source tank 130.

At step 606, controller 198 compares the level of the recovered liquid in recovery tank 118 to a second threshold using the sensor signal from high-level detector 194. If at step 608, the sensor signal from high-level detector 194 indicates that the level of liquid in the recovery tank is below the second threshold, the regenerative media does not need to be replaced yet.

At step 610, controller 198 determines if the pressure in conduit 184 has crossed a threshold using the pressure signal provided by pressure sensor 190, which is connected to conduit 184. As regenerative media filters 148 and 150 filter the recovered liquid, the material filtered out of the recovered liquid collects on and in the cake of filter media and slows the rate of liquid flow through the regenerative media filters, thereby increasing the pressure in conduit 184. If the pressure has not crossed the threshold at step 612, controller 198 returns to step 601 to determine if the level of the liquid in recovery tank is below the first threshold. Steps 601 through 612 are repeated until the pressure in the conduit exceeds the threshold indicating that the regenerative media layer on regenerative media filters 148 and 150 needs to be regenerated to thereby improve the fluid flow through the regenerative media filters. The first step of regenerating the media layer involves controller 198 setting a regeneration timer 500 (FIG. 5) at step 614. At step 616, controller 198 regenerates the regenerative media filters by turning off filter pump 138, shifting valve assembly 142 into a “regenerate” position so that conduit 184 is connected to fluid path 151 instead of being connected to the fluid path to filter pump 138, closing bypass valve 162 and opening source valve 161 and air vent valve 163. This forms a back flow path from source tank 130 to recovery tank 118 (which is under a vacuum) through regenerative media filters 148 and 150, regenerative media reservoir 146, valve assembly 142 and fluid path 151. It also allows air (from atmosphere) to enter the system through valve 163 and flow into regenerative media filters 148 and 150.

As shown in FIG. 10, this places mobile surface cleaner 100 in a “regenerate” configuration where liquid from source tank 130 and air from atmosphere are drawn through regenerative media filters 148 and 150 due to the low pressure provided in recovery tank 118 by vacuum source 120. As the air and liquid from source tank 130 are drawn through regenerative media filters 148 and 150, the action of reverse flow dislodges the layer of compacted regenerative media from the screens of regenerative media filters 148 and 150 and at least some of the regenerative media and contaminants trapped by the media are drawn toward recovery tank 118. The liquid and the dislodged regenerative media flow from regenerative media filters 148 and 150 into reservoir 146 and then through valve assembly 142 to fluid path 151. In one example, timer 500 is set to expire so that the dislodged regenerative media does not reach recovery tank 118 during the regeneration. By having the dislodged regenerative media pass through reservoir 146, it takes longer for the regenerative media to reach recovery tank 118 and allows the regeneration to be performed for a longer period. In addition, the agitation and mixing action of being drawn into and dispensed again from reservoir 146 serve to suspend the media more completely in the fluid and promote a more even re-coating of the filter septa. In other embodiments, the regeneration cycle permits the backflow of liquid and filter media into recovery tank 118.

One aspect of the embodiment of FIG. 10 is that vacuum source 120 is being used to draw liquid from both surface 104 and from source tank 130 at the same time. As a result, regenerative media filters 148 and 150 are regenerated while cleaning machine 100 continues to dispense liquid from tank 130 to clean surface 104 and recover liquid into tank 118. In other words, there is no interruption in the surface cleaning during filter regeneration.

As shown by the solid arrows in FIG. 8, when the filtered liquid from source tank 130 is drawn back through a regenerative media filter such as regenerative media filter 300 during regeneration, it enters port 310, passes into hollow chambers 319 of septum 306 and flows out through support 318 and screen 320. As the filtered liquid flows through screen 320, it dislodges regenerative media layer 800 and the contaminants trapped on the exterior of regenerative media layer 800. The liquid and the dislodged regenerative media then exit filter 300 through hole 312 and port 308.

As shown by the solid lines in FIG. 9, when filtered liquid from source tank 130 is drawn back through a regenerative media filter such as regenerative media filter 400 during a regeneration, the filtered liquid enters port 422 and passes through hollow chamber 416 of septa 406, 408, 410 and 412 to dislodge regenerative media layers 900, 902, 904 and 906 as well as the contaminants trapped by those regenerative media layers. The filtered liquid and dislodged regenerative media are then drawn up tube 414 and exit the filter at port 419.

In accordance with some embodiments, an additional air vent valve 163 is provided to bring air into the liquid passing through regenerative media filters 148 and 150 during regeneration. This additional valve has one port connected to the line between valve 161 and regenerative media filters 148 and 150 and another port connected to open air or optionally to pressurized air. The addition of air to the liquid increases the turbulence of the liquid, which can assist in removing the media layers from the septa. In further embodiments, valve 161 can also be closed during regeneration such that only air is used to remove the layer of regenerative material from the septa. Thus, any fluid can be used to regenerate filters 148 and 150 including a liquid, a liquid/gas mix, and gas alone.

The regeneration of the filter continues at step 616 until the timer set at step 614 expires at step 618. At that point, controller 198 resets valve assembly 142 to the “filter” position so that conduit 184 is in fluid communication with the fluid path from fluid pump 138 and is no longer in communication with fluid path 151. Controller 198 also closes valves 161 and 163 and opens valve 162 and turns pump 138 on again to restore the flow of fluid from the recovery tank 118 through reservoir 146 and filters 148 and 150 and back to recovery tank 118. As the liquid passes through filters 148 and 150, a new layer of regenerative media is formed in filters 148 and 150 and begins to filter recovered liquid from recovery tank 118. Until a new layer is formed, the liquid passing through filters 148 and 150 is only partially filtered. By having valve 161 closed and valve 162 open when pump 138 is restarted, this partially filtered liquid is prevented from entering source tank 130 and instead the partially filtered liquid is directed back to recovery tank 118. After a period of time, such as ninety seconds in some embodiments, the new layer of regenerative material has been established on the screens of filters 148 and 150 and if the fluid level in tank 118 is high enough to trip low level detector 192 then the controller 198 opens valve 161 while closing valve 162 to direct the filtered liquid into source tank 130.

The process of steps 601, 602, 603, 604, 606, 608, 610, 612, 614, 616, 618 and 620 continue for multiple cycles. With each cycle, the amount of contaminants filtered by regenerative media filters 148 and 150 increases. The increase in contaminants reduces the rate at which fluid flows through regenerative media filters 148 and 150 during filtering. This reduction in the fluid flow and increasingly frequent regeneration cycles will eventually cause the level of liquid in recovery tank 118 to exceed the second threshold at step 608 as indicated by high level detector 194. At this point, recovery tank 118 is considered “full” and vacuum source 120 is automatically turned off to prevent liquid from entering vacuum source 120 at step 609. Since a full recovery tank 118 is a result of the filter regeneration cycle being unable to keep up with the amount of liquid being drawn into recovery tank 118, when vacuum source 120 is turned off it is an indication that the filter system needs to be cleaned and the regenerative media needs to be replaced with new regenerative media. In accordance with some embodiments, an additional indication that the regenerative media needs to be replaced is provided using change filter media indicator 196, which can be a visual indicator and/or an auditory indicator. Thus, in this context, high level detector 194 provides a measure of the condition of the regenerative media filters. Instead of using high level detector 194, other measures such as a count of the number of regeneration cycles or a measurement of the rate of liquid passing through regenerative media filters 148 and 150 may be used instead. In any case, however, when the machine can no longer dispense water (because the source tank is empty) or recover it (because the recovery tank is full), the cleaning cycle is over and filters 148 and 150 should be cleaned and the regenerative media should be replaced.

The state of mobile surface cleaner 100 at step 609 in accordance with such embodiments is depicted in FIG. 11. As shown in FIG. 11, controller 198 has turned off vacuum source 120 and dispensing pump 132 so that cleaning liquid is no longer being sprayed on surface 104 and liquid is no longer being recovered from surface 104. Change filter media sensory indicator 196 is active and is conveying to a user that the regenerative media needs to be replaced. Although change filter media sensory indicator 196 is shown as being part of mobile surface cleaner 100, in embodiments where mobile surface cleaner 100 is autonomous, change filter media sensory indicator 196 may be provided on a remote device that is accessed by a person.

To replace the regenerative media, the user dumps the recovered liquid in recovery tank 118 using an outlet port 1100. The user then removes and rinses out the removable bowls of containers 304/404 (FIGS. 3 and 4) of regenerative media filters 148 and 150. The user also cleans the filter screens (septa 318 or 406, 408, 410 and 412) to remove all of the contaminants and regenerative media from the screens. In one embodiment, filters 148 and 150 are mounted in mobile surface cleaner 100 so that a backsplash is provided behind filters 148 and 150 to allow the filter screens to be hosed off in situ on the cleaner without affecting other components of mobile device 100. In another embodiment these bowls or housings of filters 148 and 150 are fixed and the filter elements are themselves removable to allow them to be rinsed off in a sink or by other appropriate means. In either case the used media must be removed and the screens rinsed clean to prepare for another cycle of operation with new media. The user also removes and drains container 202 from regenerative media reservoir 146 and cleans the interior of container 202 before refilling removable container 202 with new regenerative media.

In accordance with one embodiment, removable container 202 is filled with regenerative media using a sealed pre-measured container. Using such a container, the user opens the container and dumps the entire contents of the container into removable container 202. In other embodiments, removable container 202 is a disposable container and instead of washing container 202, the user simply discards container 202, opens a new sealed container 202 that contains new regenerative media and installs the new disposable container 202 by connecting it to cap 204. Once recovery tank 118 has been emptied, regenerative media filters 148 and 150 have been cleaned and new filter media have been installed in removable container 202, mobile surface cleaner 100 is reset and new source liquid is added to source tank 130 and recovery tank 118. Regenerative media filters 148 and 150 are then primed at step 600 of FIG. 6 and mobile surface cleaner 100 may then be used once again for cleaning surfaces.

FIG. 12 illustrates a mobile hard floor surface cleaner 1200 in accordance with one or more exemplary embodiments of the present disclosure.

In one example, cleaner 1200 is substantially similar to the T5 Scrubber-Dryer of Tennant Company as shown and described in the T5 Operator Manual Rev. 06, dated 2008, and the T5 Parts Manual Rev. 06, dated 2008, for example, which has been modified to include the recovered liquid filter system shown or described herein.

In this example, cleaner 1200 is a walk-behind cleaner used to clean hard floor surfaces, such as concrete, tile, vinyl, terrazzo, etc. Cleaner 1200 could alternatively be designed as a ride-on, autonomous, attachable, or towed-behind cleaner for performing a scrubbing operation as described herein. In a further example, filtration and recycling as described in the preceding section could be adapted to work on a mobile cleaning platform designed to clean soft floors, such as carpet, or both hard and soft floors in further embodiments. Such a cleaning device may include electrical motors powered through an on-board power source, such as batteries, or through an electrical cord. Alternatively, for example, an internal combustion engine system could be used either alone, or in combination with, the electric motors.

Cleaner 1200 generally includes a base 1202 and a lid 1204, which is attached along one side of the base 1202 by hinges (not shown) so that lid 1204 can be pivoted up to provide access to the interior of base 1202. Base 1202 includes a source tank 130 for containing a liquid or a primary cleaning and/or sanitizing liquid component (such as regular tap water) to be treated and applied to the floor surface during cleaning/sanitizing operations. Alternatively, for example, the liquid can be treated onboard or offboard cleaner 1200 prior to containment in tank 130. Tank 130 can have any suitable shape within base 1202, and can have compartments that at least partially surround other components carried by base 1202.

Base 1202 carries a motorized scrub head 1210, which includes one or more scrubbing members 1212, shrouds 1214, and a scrubbing member drive 1216. Scrubbing member 1212 may include one or more brushes, such as bristle brushes, pad scrubbers, microfibers, or other hard (or soft) floor surface scrubbing elements. Drive 1216 includes one or more electric motors to rotate the scrubbing member 1212. Scrubbing members 1212 may include a disc-type scrub brush rotating about a generally vertical axis of rotation relative to the floor surface, as shown in FIG. 12. Alternatively, for example, scrubbing members 1212 may include one or more cylindrical-type scrub brushes rotating about a generally horizontal axis of rotation relative to the hard floor surface. Drive 1216 may also oscillate scrubbing members 1212. Scrub head 1210 may be attached to cleaner 1200 such that scrub head 1210 can be moved between a lowered cleaning position and a raised traveling position. Alternatively, for example, cleaner 1200 can include no scrub head 1210 or scrub brushes.

Base 1202 further includes a machine frame 1217, which supports source tank 130 on wheels 1218 and castors 1219. Wheels 1218 are driven by a motor and transaxle assembly, shown at 1220. The rear of the frame carries a linkage 1221 to which a fluid recovery device 116 is attached. In the embodiment of FIG. 12, the fluid recovery device 116 includes a vacuumized squeegee 1224 that is in vacuum communication with an inlet chamber in recovery tank 118 through a hose 1226. The bottom of source tank 130 includes a drain 1230, which is coupled to a drain hose 1232 for emptying source tank 130. Similarly, the bottom of recovery tank 118 includes a drain 1233, which is coupled to a drain hose 1234 for emptying recovery tank 118. Alternatively, for example, one or both of the source tank and recovery tank and related systems can be housed in or carried by a separate apparatus.

In a further embodiment, cleaner 1200 is equipped without a scrub head, wherein the liquid is dispensed to floor 1225 for cleaning or sanitizing without a scrubbing action. Subsequently, a fluid recovery device recovers at least part of the dispensed liquid from the floor and conveys it into recovery tank 118.

In another embodiment, cleaner 1200 includes a wand sprayer and extractor or other attachment (not shown) that can be used to clean off-floor surfaces.

Cleaner 1200 can further include a battery compartment 1240 in which batteries 1242 reside. Batteries 1242 provide power to drive motors 1216, vacuum source 120, and other electrical components of cleaner 1200. Vacuum source 120 is mounted on the underside of recovery tank 118. A control unit 1246 mounted on the rear of the body of cleaner 1200 includes steering control handles 1248 and operating controls for cleaner 1200.

Cleaner 1200 also includes a filter system for filtering the recovered liquid in recovery tank 118 and providing the filtered liquid to source tank 130. In particular, cleaner 1200 includes filters 122, 126, and 140 in recovery tank 118, filter pump 138, valve assembly 142, regenerative media reservoir 146, regenerative media filters 148 and 150, bypass valve 162, source tank valve 161 pressure sensor 190 and level detectors 192 and 194, which all operate in the same manner as discussed above for FIGS. 1-11. Further, controller 198 is present within control unit 1246 and is powered by batteries 1242. Valve assembly 142, valves 162 and 161, filter pump 138, pressure sensor 190 and level detectors 192 and 194 are also powered by batteries 1242.

Base 1202 and lid 1204 include hinged front covers that may be opened to provide access to regenerative media reservoir 146 and regenerative media filters 148 and 150. In particular, with the front covers open, it is possible to remove removable container 202 from regenerative media reservoir 146, install new regenerative in container 202 while it is removed, and reinstall newly-filled removable container 202 in machine 1200. Further, the containers of regenerative media filters 148 and 150 may be removed when the front cover is open and the filter screens of those filters may be cleaned without removing the septa from cleaner 1200. In accordance with some embodiments, windows are provided in the front cover to allow the condition of the regenerative media filters to be monitored.

FIG. 13 provides an alternative construction of regenerative media filters 148 and 150 and regenerative media reservoir 146. Although only two regenerative media filters 148 and 150 are shown in FIG. 13, those skilled in the art will recognize that in some embodiments only a single regenerative media filter is present while in other embodiments, more than two regenerative media filters, for example, four regenerative media filters, are present.

In FIG. 13, conduit 184 from valve 142 is releasably connected to media reservoir 146 through a quick connect 1300 having a release button 1302. Quick connect 1300 is connected to an elbow joint 1304 that is in turn connected to a cap 1306. The interior of conduit 184 is in fluid communication with the interior 1308 of reservoir 146 through quick connect 1300, elbow 1304, and the conduit in cap 1306.

Regenerative media filters 148 and 150 are connected by conduits 1310 and 1312 to a manifold 1314, which in turn is connected to a conduit 1316. Conduit 1316 includes a quick connect 1318 having a release button 1320 wherein quick connect 1318 is releasably connected to an elbow 1322 on cap 1306. Thus, the interior of reservoir 146 is fluidly coupled to conduit 1316, manifold 1314, conduits 1310 and 1312 and the interior of regenerative media filters 148 and 150. In the embodiment shown in FIG. 13, conduits 1310 and 1312 are mounted to a bottom of regenerative media filters 148 and 150. Conduit 159, which connects to valves 161, 162 and 163 in FIG. 1, is connected to regenerative media filters 148 and 150 through respective quick connects 1320 and 1322. Quick connects 1320 and 1322 are releasably connected to elbows 1324 and 1326 of filters 148 and 150 and may be released using release buttons 1328 and 1330, respectively. Elbows 1324 and 1326 are coupled to respective caps 1332 and 1334 of regenerative media filters 148 and 150. The interior of conduit 159 is in fluid communication with the interior of filters 148 and 150 through passageways in quick connects 1320, 1322, elbows 1324, 1326, and caps 1332 and 1334.

FIGS. 14-20 provide a perspective view, a front view, a back view, a left side view, a right side view, a sectional view and exploded side view, respectively, of a regenerative media filter 1400 which can be used as regenerative media filters 148 and 150 in FIG. 13. As shown in FIG. 20, regenerative media filter 1400 includes canister structure 1402 and filter assembly 1404. Filter assembly 1404 includes septa 1406, 1408, 1410, 1412, 1414, 1416, 1418, 1420, 1422 and 1424. Septa 1406-1424 have a similar structure to that described above for septa 406, 408, 410 and 412. In particular, each septa has a support structure that defines a hollow chamber and one or more screen layers which are secured around the support structure. These screen layers are constructed of woven stainless steel in one embodiment but may be constructed of woven nylon or any other resilient screening material with sufficiently small openings to prevent the regenerative material from passing while allowing liquid to pass. Each of the septa are supported by a plate 1426 that includes an opening for each septa. Plate 1426 is connected to a manifold 1428 which in turn is connected to a cap 1430. Cap 1430 includes an opening 1432 which is connected to elbows 1324 and 1326 in FIG. 13. Opening 1432 is the opening of a conduit 1434 that extends within cap 1430 to an internal chamber 1436. Chamber 1436 in turn communicates with manifold slots 1438, 1440, 1442 and 1444 of manifold 1428. Each manifold slot 1438, 1440, 1442 and 1444 communicates with one or more holes through manifold 1428, with a separate hole for each septum, such as holes 1446 and 1448 for septa 1422 and 1424.

Two pins 1450 and 1452 extend radially outward from cap 1430 to engage a locking mechanism 1454 at the top of canister structure 1402. In one embodiment, locking mechanism 1454 and pins 1450 and 1452 form a bayonet mount in which pins 1450 and 1452 enter two channels 1460 and 1462 in respective catches 1456 and 1458. To engage filter assembly 1404 on canister structure 1402, cap 1430 is pressed down while pins 1450 and 1452 are placed into channels 1460 and 1462. A twisting motion is then applied which forces cap 1430 further down into canister 1402 and locks cap 1430 in place. Cap 1430 and filter assembly 1404 are removed from canister structure 1402 by reversing this process.

In canister structure 1402, locking mechanism 1454 is mounted to the top of a cylinder 1476, which in many embodiments is made of a clear plastic. The bottom of cylinder 1476 is sealed by a plate 1470 having a spigot 1474 mounted thereto. Spigot 1474 includes an attachment neck 1475 that can be attached to a conduit. Bottom plate 1470 includes an opening 1471 that is in fluid communication with a conduit defined within spigot 1474 and is thus in fluid communication with any conduit attached to spigot 1474. Manifold 1472 is attached to bottom plate 1470 and includes an opening 1473 that is mounted above opening 1471 in bottom plate 1470. Opening 1473 is in fluid communication with a plurality of chambers in manifold 1472, such as chambers 1475 and 1477. Supports 1480, 1482, 1484 and 1486 provide additional structural support between locking mechanism 1454 and bottom plate 1470.

During filtering, fluid enters through spigot 1474 and opening 1471 in baseplate 1470. It then travels through opening 1473 in manifold 1472 and is disbursed by chambers 1476 and 1477 in manifold 1472. The fluid then passes into the interior of cylinder 1476 where it passes through the layers of regenerative material and the screen meshes on septa 1406-1424 to reach the interiors of the septa. As the fluid passes through the layers of regenerative material and the screen meshes it is filtered to remove contaminants in the fluid. The fluid then flows up through the interior of the septa to the openings in manifold 1428 and then into chamber 1436 of cap 1430 before exiting through conduit 1434 and opening 1432. During regeneration, this fluid flow is reversed.

When regeneration is no longer sufficient to clean the regenerative media filters of FIGS. 14-20, filter assembly 1404 is removed from canister structure 1402 by disconnecting the quick connect such as quick connect 1320, 1322 using buttons 1328 and 1330, respectively. Cap 1430 is then twisted and lifted to release it from locking mechanism 1454 and filter assembly 1404 can be placed in a bucket or a sink. The exteriors of the septa can then be rinsed and scrubbed to remove the layer of regenerative material from the septa.

Canister structure 1402 may be cleaned by disconnecting conduit 1316 from media reservoir 146 using quick connect 1318 and placing conduit 1316 in a drain. Water is then poured into canister structure 1402 to wash out regenerative media and contaminants.

As described above, in accordance with one embodiment, the regenerative material is provided in a paste form. FIG. 21 provides a sectional view showing a plug 2100 of regenerative material paste being inserted into a regenerative media reservoir 146. Plug 2100 is shipped within a canister 2102 having a cylinder 2103, a top cap (not shown), and a bottom cap 2104. To load plug 2100, cap 1306 is disengaged from a locking mechanism 2106 of reservoir 146 and the top cap of canister 2102 is removed. Cylinder 2103 is then inverted and inserted into the inner diameter of locking mechanism 2102 such that the top surface of cylinder 2103 is proximate the top surface of cylinder 2108 of reservoir 146. In accordance with one embodiment, cylinder 2103 is shaped and sized such that a cylindrical inner surface 2110 of cylinder 2103 is aligned with a cylindrical inner surface 2112 of cylinder 2108. Cap 2104 is then removed thereby allowing plug 2100 to slide into cylinder 2108. When plug 2100 has sufficiently exited cylinder 2103, cylinder 2103 may be removed and cap 1306 may be replaced in locking mechanism 2106.

The apparatus for replacing the regenerative material shown in FIG. 21 produces no dust and thereby reduces the environmental hazard associated with airborne particles of some regenerative materials.

Although the system for filtering recovered water has been described in detail relative to cleaners 100 and 1200, those skilled in the art will recognize that the system may be implemented in any cleaner that has both a source tank of liquid and a recovered tank of liquid such as carpet cleaners, hard surface scrubbers, bathroom cleaners, and truck-mounted cleaners. In truck-mounted cleaners, the source tank, the recovery tank and the filter system are mounted within a truck and scrubbers are connected to the tanks by hoses and are brought into a building for cleaning. All such cleaners are considered mobile surface cleaners and for truck-mounted cleaners the truck forms a mobile or movable body.

In the examples provided above, separate source tanks and recovery tanks are provided. In other embodiments, a single tank is provided that acts as both the source tank and the recovery tank. In such embodiments, two additional valve assemblies may be provided, for example. The first additional valve assembly is connected to the output of the regenerative media filters, the input of the spray pump, and a flow path from the first additional valve assembly to the second additional valve assembly. The second additional valve assembly is connected to the output of the filter pump, the input to the existing valve assembly and the flow path to the first additional valve assembly. During cleaning operations, the valve assemblies are set so that liquid from the single tank is pumped through the regenerative media filters by the filter pump and the resulting filtered water is provided to the spray pump for application on the surface to be cleaned. During regeneration operations, the valve assemblies are set such that liquid from the single tank is pumped by the filter pump backwards through the regenerative media filters and the regenerative media reservoir toward a flow path into the single tank. Other valve arrangements may also be used.

Although examples of regenerative media such as diatomaceous earth, perlite, silica dioxide, activated carbon, cellulose fiber and rice hull ash are provided above, the term regenerative media is not limited to these examples. Instead, the term regenerative media includes any media that is capable of being suspended as a slurry, forming a coating on a structure as the liquid of the slurry moves through the structure, filtering contaminants in a liquid as the liquid passes through the coating, being removed from the structure to form a new slurry, forming a new coating on the structure when liquid of the new slurry moves through the structure, and filtering additional contaminants in a liquid as the liquid passes through the new coating.

Although the present invention has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention. Also, the term “coupled” as used in the specification and claims can include a direct connection or a connection through one or more intermediate elements. 

What is claimed is:
 1. A mobile surface cleaner comprising: a mobile body configured to travel to areas to be cleaned; a dispensing system attached to the mobile body for dispensing liquid on a surface as dispensed liquid; a recovery system attached to the mobile body for recovering dispensed liquid as recovered liquid; and a regenerative media filter attached to the mobile body for filtering the recovered liquid to form filtered liquid that can be dispensed by the dispensing system.
 2. The mobile surface cleaner of claim 1 further comprising at least one back flow path through the regenerative media filter whereby fluid is passed along the back flow path to cause a redistribution of regenerative media on the regenerative media filter.
 3. The mobile surface cleaner of claim 2 wherein the recovery system comprises a vacuum source to draw liquid from a surface and to draw liquid along the back flow path to cause the redistribution of the regenerative media.
 4. The mobile surface cleaner of claim 3 further comprising a pressure sensor positioned between the recovery system and the regenerative media filter.
 5. The mobile surface cleaner of claim 4 further comprising a controller that controls whether the regenerative media filter filters recovered liquid to form filtered liquid or liquid passes through the back flow path to redistribute the regenerative media based at least in part on a sensor signal provided by the pressure sensor.
 6. The mobile device of claim 5 further comprising at least one valve assembly such that: in a first configuration, the valve assembly connects the recovery system to the delivery system through the regenerative media filter to permit liquid from the recovery system to be filtered by the regenerative media filter to produce filtered liquid; and in a second configuration, the valve assembly connects the delivery system to the recovery system through the regenerative media filter to permit liquid from the delivery system to back flow through the regenerative media filter.
 7. The mobile surface cleaner of claim 1 further comprising a regenerative media reservoir located between the recovery system and the regenerative media filter.
 8. The mobile surface cleaner of claim 7 wherein the regenerative media reservoir comprises a removable container.
 9. The mobile surface cleaner of claim 8 wherein the regenerative media reservoir comprises a disposable container.
 10. The mobile surface cleaner of claim 2 wherein the recovery system comprises a recovery tank and at least one level detector that detects when liquid in the recovery tank is above a threshold level and wherein the mobile surface cleaner indicates that the regenerative media should be replaced when liquid in the recovery tank is above the threshold level.
 11. An apparatus comprising: a movable body; a tank movable with the movable body and receiving liquid recovered from an external surface; and a regenerative media filter movable with the movable body and filtering liquid from the tank to form filtered liquid that can be dispensed on an external surface for cleaning.
 12. The apparatus of claim 11 wherein in a first state, liquid from the tank is filtered by the regenerative media filter and in a second state, filtered liquid passes back through the regenerative media filter to redistribute regenerative media.
 13. The apparatus of claim 12 further comprising a pressure sensor and a controller that controls whether the apparatus is in the first state or the second state based on a signal from the pressure sensor.
 14. The apparatus of claim 12 wherein the tank continues to receive liquid recovered from the external surface while the apparatus is in the second state.
 15. The apparatus of claim 12 further comprising a valve having three fluid path connections wherein a first fluid path connection is connected to a first path to the tank, a second fluid path connection is connected to a second path to the tank and a third fluid path connection is connected to a fluid path to the regenerative media filter and wherein the valve connects the first fluid path to the third fluid path when the apparatus is in the first state and connects the second fluid path to the third fluid path when the apparatus is in the second state.
 16. The apparatus of claim 11 further comprising a vacuum source connected to the tank to draw liquid from the external surface into the tank and to draw filtered water through the regenerative media filter when the apparatus is in the second state.
 17. The apparatus of claim 11 further comprising a regenerative media reservoir for providing regenerative media for the regenerative media filter.
 18. The apparatus of claim 11 further comprising a level detector wherein the tank stops receiving liquid from the external surface when the level detector indicates that the liquid in the tank crosses a threshold.
 19. The apparatus of claim 11 further comprising an electrolysis cell configured so that the filtered liquid is passed through the electrolysis cell before being dispensed on the external surface.
 20. A machine-implemented cleaning method comprising: dispensing liquid from a mobile cleaner on a surface to be cleaned; drawing the dispensed liquid into the mobile cleaner to form recovered liquid; passing the recovered liquid through a regenerative media filter in the mobile cleaner to form filtered liquid; and dispensing the filtered liquid from the mobile cleaner on a surface to be cleaned.
 21. The method of claim 20 further comprising: regenerating the regenerative media filter at least once without adding new regenerative media; after regenerating the regenerative media filter, passing additional recovered liquid through the regenerative media filter in the mobile cleaner to form additional filtered liquid; and dispensing the additional filtered liquid from the mobile cleaner on a surface to be cleaned.
 22. The method of claim 21 further comprising: determining that the regenerative media needs to be replaced based on a level of liquid in a tank.
 23. The method of claim 21 further comprising before regenerating the regenerative media filter, measuring a pressure in a conduit and using the measured pressure to determine that the regenerative media filter should be regenerated.
 24. The method of claim 21 further comprising adding new regenerative material by adding a paste or dissolvable cake of regenerative material to the mobile cleaner.
 25. The method of claim 21 wherein regenerating the regenerative media filter comprises using a vacuum source attached to a recovery tank to draw the filtered liquid through the regenerative media filter.
 26. The method of claim 25 further comprising while using the vacuum source attached to the recovery tank to draw the liquid through the regenerative media filter, simultaneously using the same vacuum source to draw the dispensed liquid into the mobile cleaner to form the recovered liquid. 